The proposed research is designed to characterize the oxygenation behavior of the multiple hemoglobins of the American eel, Anguilla rostrata, particularly to the effects of the two major intraerythrocytic organic phosphates of the eel: guanosine triphosphate and adenosine triphosphate. (Geoghegan 1972, Geoghegan and Poluhowich, in preparation). The individual hemoglobin components will be obtained by column chromatography (DEAE Cellulose), stripped of their organic phosphates (Chautin and Hermann, 1969), concentrated by ultrafiltration, and tested for purity by starch gel electrophoresis (Poluhowich, 1969, 1972). Dissociation curves for the hemolysate and the individual components, will be determined according to the method of Benesh, et al., (1965) with regard to alterations in temperature, pH, hemoglobin concentration, and ionic strength. These experiments will then be repeated with the addition of the two organic phosphates, individually and in combinations. The organic phosphate concentrations used will be based upon the determinations of Geoghegan (1972). The data obtained will provide a comprehensive picture of the oxygenation behavior of multiple hemoglobins and how this function is allosterically modified by the intraerythrocytic organic phosphates. Since multiple hemoglobins are common in the animal kingdom (Gratzer and Allison, 1960) and since most vertebrate erythrocytes contain organic phosphates (Bartlett, 1970), this study will provide pertinent data concerning the interaction of these compounds.